There's a reason those prices are so cheap. I've taken them several times before, NYC-BOS, LAX-PHX, LAX-SAN, LAX-LAS.
While the price is nice, there is always a concern for breakdowns. It's a risk one takes, and it has to be factored into one's decision to save a few bucks. The drivers really don't get anything like what the Greyhound drivers get, in terms of training or rest time.
Accept the fact there's a higher probability of something going wrong and determine if it's worth it.